I got a "rescue betta" from a friend 3 days ago. My little buddy had very noticeable fin rot when I got him and my friend gave me a little jar of medicine to treat him with. Later that night, I noticed that in addition to his damaged fins he has a white spot on top of his head that looks like fungus. I'm not sure the brand of the fin rot medicine I'm using right now, but my question is should I treat both at once? Or should I treat one before the other?
I'm going to petco today to buy a bigger tank and heating pad, are there any medicines that you would suggest I use which are available at petco? If not, please tell me anyway and I'll check the fish store nearby and amazon.com.
I've only had Eridan a few days but I've already fall in love with him and can't bear to see him suffer. :'( Any help will be appreciated!!
Here's the recommended info,

Housing
What size is your tank? It's a small 1 gallon fish bowl
What temperature is your tank? NA
Does your tank have a filter? No
Does your tank have an air stone or other type of aeration? No
Is your tank heated? No
What tank mates does your betta fish live with? None

Food
What type of food do you feed your betta fish? I feed him bloodworms in the morning and betta flakes in the evening
How often do you feed your betta fish? Twice a day

Maintenance
How often do you perform a water change? Every 4 days
What percentage of the water do you change when you perform a water change? 100%
What type of additives do you add to the water when you perform a water change? I add water conditioner

Water Parameters:
Have you tested your water? If so, what are the following parameters? NA

Symptoms and Treatment
How has your betta fish's appearance changed? Hasn't changed since I got him but he has a lot of fin rot and what looks like a fungus on top of his head
How has your betta fish's behavior changed? Hasn;t changed but he's pretty skittish and has difficulty eating, is that common in bettas?
When did you start noticing the symptoms? When I first got him
Have you started treating your fish? If so, how? I'm treating him with the fin rot medicine my friend gave me
Does your fish have any history of being ill? Yes, he was ill when I got him
How old is your fish (approximately)? I think he's a few months old. I got him from a friend who got him from her aunt. The aunt was taking very poor care of him and it shows.

Update: I went to Petsmart today and bought Maracyn and Maracyn two. I used both and already Eridan is more active and perky. He's been so lethargic lately but the medicine seems to have perked him up.
:)

I just moved him to the 10 gallon tank and although his fin rot and fungus don't look any better, he is definitely more active and seems to be thoroughly enjoying the extra nine gallons. :) I installed the water heater today but I added him before the tank heated up so he could ease into the temperature change.
It's day 4 of the 5 day medicine limit and not much has changed. If it doesn't seem to make a difference I'll use the old fin rot medicine my friend gave me and buy the jungle fungus remover from walmart.